1. Field of the Invention
The present invention relates generally to pouches, and particularly to a flow channel that may be used to evacuate a pouch.
2. Description of the Background of the Invention
Pouches are typically used for storage and preservation of perishable contents such as food. Perishable contents may be made to last longer with less degradation if stored under vacuum. Evacuable thermoplastic pouches have been designed to work with a vacuum source to allow storage of contents under vacuum. However, a problem with evacuating a thermoplastic pouch is that the pouch has flexible walls that are forced together into contact with one another as a result of the evacuation. Regions of the pouch interior may thus be blocked from the vacuum source by the contacting walls, making those regions difficult or impossible to evacuate. In response to this problem, evacuable thermoplastic pouches have been designed with various flow channels that function to prevent the pouch walls from coming into contact and blocking off regions of the pouch from the vacuum source.
One such pouch has a thick textured porous sheet that is affixed to an inner surface of a pouch wall over an aperture in the pouch wall. The sheet has dimensions similar to the pouch wall and functions to prevent the pouch walls from adhering to one another during evacuation. The sheet provides flow paths from the pouch interior to the aperture to prevent the pouch walls from adhering, thus preventing evacuation of the pouch. Another pouch has a strip of mesh or woven material that extends from the pouch interior to a mouth of the pouch. The strip of mesh may be inserted by a user or affixed to the pouch interior during manufacture. The strip may alternatively be comprised of a plurality of tubes held together to form the strip.
A further pouch has a strip of flexible plastic material attached to an interior of the pouch. The pouch has an aperture that extends through a wall of the pouch proximate an end of the pouch. The strip has a flat base and a plurality of ribs disposed lengthwise on one side of the base. A first end of the strip is attached to the interior of the pouch opposite the aperture. A second end of the strip is attached to a region of the interior that is at an opposite end of the pouch from the aperture. The ribs provide fluid communication between the aperture and the entire length of the strip.
Other pouches have protuberances that are extruded integrally with a sidewall or embossed onto a sidewall of the pouch between an interior of the pouch and an evacuation aperture. Each protuberance has a body that extends away from the sidewall between a base end and a distal end. The body has parallel side walls or is generally tapered from the base end to the smaller distal end. The protuberances may take the form of discrete shapes or may be joined to form ridges. The protuberances may also be arranged irregularly or formed into patterns. Channels formed between the protuberances provide fluid communication between the evacuation aperture and the interior of the pouch.
Yet another pouch has one or more wall panels that are formed from a material that is pressed between rollers to impart a corrugated cross-section to the material. Grooves and ridges formed by the rollers are imparted on an angle with respect to the direction of forming. The material is folded upon itself to form the pouch with the wall panels, wherein the pouch has grooves and ridges in each wall panel that intersect with grooves and ridges on an opposing wall panel. The intersecting grooves and ridges prevent the wall material from flattening under evacuation, thereby creating air channels throughout the pouch.
Still another pouch has a pattern of channels on a sidewall that is created by pressing a melt-extruded resin between rollers. The channels have baffles that allow gases to escape from the pouch, yet trap liquid within the pouch. Another pouch has at least one sidewall that has a zigzag pattern of channels or ridges formed therein or thereon, respectively.
Pouches that have flow channels may have regions of the pouch interior blocked from a vacuum source by an opposing sidewall that has entirely collapsed into a channel due to the inherent flexibility of the opposing sidewall material. Narrower flow channels can lessen blockage caused by the collapsed opposite sidewall, but also have decreased flow volume. Sidewalls made of more rigid material can also lessen blockage by limiting collapse, but necessarily have less flexibility.